Armament for jet aircraft



6, 1 3 E. v. MARSHALL ETAL 3,099,938

ARMAMENT 'FOR JET AIRCRAFT Filed April 30. 1957 2 Sheets-Sheet 1 INVENTORS EDMUND V. MARSHALL WILL S. UAVIES y r mmvE'w Aug. 6, 1963 E. v. MARSHALL ETAL 3,099,938

ARMAMENT FOR JET AIRCRAFT Filed April 30. 195? z Sheets-Shet 2 Fig. 3

F I 4 INVENTORS EDMUND V. MARSHALL WILL S. DAVIES ite The rapid development of jet aircraft in recent years had caused a number of problems to arise in connection with the mounting of armament thereon. This is particularly true in regard to certain types of remotely-controlled guns carried in the body of such craft, and is occasioned by the particular operating characteristics and requirements of jet engines. In addition to the obvious undesirability of employing any apparatus or structure which will create excessive air turbulence and hence a reduction in plane speed and/ or maneuverability, there is the necessity of precluding the entrance of gun blast gases in any appreciable amount into the air intake of the jet engine. When such precautions are not taken, there is a reaction between these gun blast gases and certain of the metallic operating parts of the engine which materially increases the amount of repair and servicing work required to maintain the aircraft in flight condition.

The use of blast tubes on guns or firearms to absorb excessive recoil energy is well known to workers in this field, as is the use of air deflectors on certain types of aircraft to aid in cooling the gun barrel by speeding the exhaust blast gases into the air stream. In all known instances, however, these solutions have failed to take into account the immediate proximity of a jet engine air intake. When the latter is present, normal methods of handling the gun problem are no longer applicable, and the gun blast assembly must be especially designed with the above structural relationship in mind.

The difliculty is enhanced by the fact that the outer surface configuration of a conventional jet engine air in take scoop is such that the mounting of a gun or guns Within this scoop causes each projectile opening to appear very close to, or even partially within, the normal boundaries of the air intake orifice. Consequently, gun blast gases in appreciable amounts are very readily sucked into the engine air intake duct during flight unless these gases are in some way prevented from reaching the projectile openings.

In presenting a solution to the above problem, the present disclosure incorporates an opening of generally ovoid configuration extending between the outer surface, or skin, of the jet engine air scoop and the blast tube through which the projectile passes after it leaves the gun muzzle and before it emerges from the projectile opening. This generally transverse opening in the scoop body accordingly forms a communication path between the gun blast tube and the outer surface of the air scoop, this air passage being located to the rear of the opening in the air scoop through which the projectile emerges.

It is recognized, however, that such an unmodified transverse air passage per so does not act to fully exhaust the gun blast gases therethrough, and, in addition, its presence tends to create excessive air turbulence over that portion of the outer surface of the air scoop located in its immediate vicinity. Consequently, to complete the effective dissipation of these gaseous waste substances without reducing plane speed to any appreciable degree, the present invention incorporates, in each transverse opening connecting a gun blast tube to the outer surface of the air scoop, a plurality of baflles in the form of cupshaped gas deflectors. These deflector elements are oriented with their convex surfaces aligned in the direction of aircraft flight, such that the outer edge of each baffle does not project beyond the boundary defined by an extension of the surface skin of the air scoop. Thus, the baffles act to deflect the blast gases emitted from the gun muzzle through the opening extending transversely between the blast tube and the outer surface of the scoop, and this gas scavenging action is accomplished with minimum disturbance of the normal air flow pattern over the scoop surface. Moreover, the point at which these blast gases are exhausted is rearward of the jet engine air intake orifice, so that substantially none of the gun blast gases so exhausted enters the jet engine operating mechanism as may readily be the case in conventional jet aircraft constructions.

One object of the present invent-ion, therefore, is to improve the operating characteristics of jet aircraft carrying at least one remotely-controlled gun in an air intake associated with the aircraft fuselage.

Another object of the invention is to provide an arrangement for jet aircraft whereby blast gases from armament carried in a jet engine air intake scoop on such craft are precluded from entering the orifice of the air scoop to adversely affect the engine operation.

A further object of the invention is to provide a passage for gun blast gases from a blast tube, located within the jet engine air intake scoop of an aircraft, to the surface of such scoop, together with a plurality of deflecting elements within said passage so arranged and constructed as to facilitate the evacuation of such gases without causing excessive turbulence in the air stream flowing over the scoop surface.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understod by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a perspective view of applicants invention as applied to an aircraft having a jet engine air intake scoop associated with the aircraft fuselage, together with a pair of remotely-controlled guns mounted within such air scoop;

FIGS. '2 and 3 are detailed perspective views of a portion of FIG. 1; and

FIG. 4 is :a longitudinal view in cross-section of one of the gun blast gas deflecting arrangements illustrated in FIGS. 1, 2, land 3.

Referring now to the drawings, there is shown in FIG. 1 an aircraft of the jet-propelled type. To simplify the ensuing description, reference will be made herein only to those portions of the aircraft which are pertinent to an understanding of the present invention. Such portions include an air intake scoop, generally identified by the reference numeral 10, extending outwardly from the lefthand side of the aircraft fuselage 12 and adapted to provide an air supply for one of the crafts two jet engines (not shown). This air intake scoop 10 consists of a body member 14 through which a tube or duct passes from a forward orifice 16 to the jet engine operating mechanism contained within the fuselage 12. Such a mode of construction is more or less standard in the aircraft industry, and no further discussion of this arrangement is believed necessary.

The aircraft of the drawings is armed with four remotely-controlled machine guns, two of which are located within the body of each of the twin jet engine air intake scoops. The left-hand scoop 10 of FIG. 1 contains the guns l8 and 20-, positioned somewhat as shown in dotted outline, with their barrels generally aligned with the longitudinal axis of the aircraft.

The gun mechanisms 18 and 20 are respectively provided with openings 22. and 24- in the outer surface, or skin, of the air intake scoop body 14 to permit passage there- 3 through of projectiles fired by these guns. As will be noted in FIG. 1, the generally ovoid configuration of the outer surface of the forward portion of the air scoop necessitates a location for the projectile openings 22 and 24 which is on, or in close proximity to, the periphery of the orifice -16 through which air passes to one of the jet engines of the aircraft. This proximate relationship can only be avoided by relocating the machine guns or by restricting thesize :of-the orifice 16, and neither expedient is-practical in many cases due both to the over-all size of the firearms and to the large volume of air required by conventionaljetmotors for maximum operating efliciency.

When'either or both of the guns 18 and 20 fire, blast gases are emitted from the muzzle or muzzles thereof. Repeated firing of such guns normally causes a relatively large amount of this gas to emerge from the projectile openings 22 and/or 24. It will be apparent from an inspection of the drawing that, whenever the aircraft is in flight, at least aportion of these blast gases will be sucked into the neighboring air intake orifice 16 and hence conducted to the jet engine operatingmechanism. As previously stated, experience has shown these gun blast gases to have a deleterious effect on certainmet-allic components .of the engine, causing corrosion or other damage to these parts.

To overcome this undesirable condition, the present disclosure provides means for precluding the emergence of gun blast gases in any appreciable amount from the projectile openings 22 and 24. This arrangement is shown in enlarged perspective in FIGS. there is illustrated in cross-section a conventional blast tube 26 which is located within the body 14 of the air scoop and which extends longitudinally from the muzzle 28 of gun 20 to the projectile opening 24. The inner end of blast tube 26 is flared asshown to receive the barrel of gun 20. Since substantially identical gas deflecting devices according to this invention are employed for each of the four guns of the aircraft, only one such arrangement will be described hereinafter.

Inorder to prevent the gases emitted .into the blast tube 26 (for example) from emerging from the projectile opening 24, these gases must be removed from the blast tube before they reach this point. This is brought about, in the embodiment illustrated, by means which includes a transverse opening, or passage, 30 in the body 14 of air scoop 10. This opening 30 extends from the outer suriace, or skin, of the air scoop to communicate with the gun glast tube 26. While the configuration and dimensions of this transverse opening are not critical, the passage should be of :suflicient size so that blast gases may be deflected therethrough in the manner to be set forth below.

As shown, however, the opening 30 .(see especially FIGS. 2 and 4) is of generally ovid configuration, having a wall composed of three separate sections-a top portion 32 defined by a sunfiace which is flared outwardly, a central portion 34 defining a generally vertical surface, and a bottom portion 36 defined by a surface again outwardly flared. These sections may be welded both to one another and to the scoop body 14, or any other means may be employed i or securing them in position. Inasmuch as the passageway 30 is formed in the generally ovoid body 14 of the air scoop, the intersection of its wall portions, both vwith the outer scoop surface and with the gun'blast tube v26, will be irregular in outline, as perhaps best brought out in FIG. 2.

Associated with the transverse passage 30 in the body :14 of the air scoop are two bafiles 38 and 40. These bafiles roughly define a portion of a spherical surface,

being generally convex in the direction-of .aircrazfit flight. The edges of the bafiles are shaped to conform to the surfaces of the walls 32, 34, and of the transverse opening 30331 the points where they are to .be securely positioned therein, as by welding or any other suitable method. Furthermore, the outer edges of baffles 38 and 40 are soaligined with'the outer surfaceskin of the air scoop 2 and 3, while in FIG. 4

' convex in the direction of aircratt flight; and

i 10 that no excessive air turbulence is created by their presence.

It will now be appreciated that the blast gases emitted from the muzzle 28 of gun 20, in traveling to the pro jectile opening 24 of blast tube 26, will encounter the baffle elements 40 and 38 in that order. Due to the cup-shaped configuration of these bafiles, they will act as scoops to intercept substantially all of these blast gases, convey them through passage 30, and eject them into the air stream flowing over the outer surface skin of the air scoop body 14. The above action is enhanced by the suction created within passage 36 as the surface air stream flows over the outer edges of the baffles. As a consequence of this scavenging of the blast gases through passageway 30, substantially none of these gases reach the projectile opening 24, and hence very little, if any, blast gas is drawn into the jetengine air intake orifice 16. The objective of the invention is thus accomplished.

, It i obvious that, if desired, the baffles 38 and 40 may be made up of individual sections welded together or otherwise formed into a single unit. Furthermore, these separate sections need not have curved surfaces, but instead can consist of flat platesvangular-ly joined to gen erally outline the same portion of a cup-shaped or spherical surface illustrated in the drawings. It is only necessary that these cup-shaped gas deflectors 38 and 40 be so configured and positioned as to act as scoops for the blast gases traveling forward within the blast tube 26.

It will also be appreciated that the number of bafiles employed will depend at least in part on the diameter of the blast tube 26, on the amount of gas emitted by the gun 20, and on the proximity of the projectile opening 24 to the air intake orifice 1-6. Occasionally only one bafiie may suflice, and 'again more than two may be necessary. Obviously the size and internal dimensions of the transverse passage 30' will also be determined with the above considerations in mind.

Many modifications of and variations in the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claim the invention may be practiced otherwise than as specifically described.

I claim:

The combination on an aircraft propelled by at least one jet engine: anair intake scoop for said jet engine extending generally longitudinally of said aircraft; at least one remotely-controlled gun enclosed within said air intake scoop; a blast tube for said gun, said blast tube extending generally longitudinally of said aircraft from the muzzle of said gun to a projectile opening in the surface of said air scoop locatedon, or in close proximity to, the periphery of the jet engine air intake orifice; a generally transverse passage in the body of said scoop extending from the outer surface Olf the latter to communicate [with the said gun blast tube, the rearward wall portion of such transverse pass-age defining a surface which is generally a pair of baffles lying within said transverse passage and secured to the wall thereof said baffles each being formed to define a surface which is also generally convex in the direction of aircraft 'ilight, such that a scavenging action is brought about within said transverse passage with respect to the gases emerging from the muzzle of said gun into said blast tube when the former is fired to thereby precliude the emergence of such gases in an appreciable amount from said projectile opening into the vicinity of said jet engine air intake orifice.

References Cited in the file of this patent .UNITED STATES PATENTS 

